1. Field of the Invention
This invention relates generally to a pneumatic tool and vibration isolator mounts therefor. In particular, this invention relates to pneumatic tool and vibration isolator mounts which are adapted for mounting between the handle of the pneumatic tool and the tool housing to thereby reduce vibration transferred to the user.
2. Description of Prior Art
One of the difficulties of arriving at a vibratory isolator in a power tool is the problem of where to place the vibratory isolator in the tool. Some prior art devices have addressed this concern by placing the isolators in the housing, whereas others have placed the isolators at a joint between the grip handles and the housing.
In one particular prior art tool, an outer casing of rigid material is formed with a bell-shaped cavity therein. A motor housing is disposed in the cavity and isolated from the casing by elastomeric vibration-absorbing material which is pourable into the bell-shaped cavity between the motor housing and the outer casing. As the material cures, it becomes bonded to the interior surface of the casing and to the outer surface of the motor housing. The difficulty with this arrangement is that once the parts are bonded, they are difficult to interchange. Another drawback is that excessive vibration-absorbing material is required.
Another prior art vibratory dampening device on a power tool includes a dampening arrangement on a joint between a grip handle and a handle holder attached to the housing of the power tool. In this embodiment a large diameter shaped cup on a grip handle is disposed radially around the handle holder. Either the handle holder or grip handle includes radially outward or inward extending flanges to engage elastomeric vibration isolating dampers between the grip handle and the handle holder. This type of power tool is not usable with pneumatic tools since it lacks any features for providing a pneumatic seal between the grip handle and the handle holder.
One prior art pneumatic device discloses a pneumatic seal between the grip handle and the handle holder in a reciprocating pneumatic hammer. In this device, a handle is isolated from the body of the tool by a vibratory isolator. The isolator includes a rubber cushion member bonded to two steel coupling members, one of which is bolted to the handle and the other is bolted to the body of the tool. An air passageway extends through the handle and the cushion member for passage of air to reciprocate the hammer. Within the cushion member is an insert to provide an annular seal around the air pressure passage. A disadvantage of this device is that it is formed as an integral unit which may result in loss of sealing capabilities upon breakage. This joint is also designed for axially reciprocating loads and thus is questionable as to whether it could withstand substantial shear or torsional stresses when used with non-reciprocating pneumatic tools.